Mathematical and numerical analysis are applied to a nonlinear operator equation arising in monetary economics. For the nonlinear operator equation, the contraction property is established, and fixed point iterations are employed to numerically solve the equation using a finite element method. Convergence rate and error estimates are given for the numerical scheme. The finite element method has been implemented as computer programs which make extensive use of computer software packages such as Maple (for numerical computations and graphics) and Mathematica (for symbolic computation).